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Explain three ways in which the structure of the xylem vessels makes them well-adapted to their function.

The end walls are removed from each end, forming an uninterrupted tube, so water can pass through easily.Their walls are thickened with a woody substance called lignin , which helps to support the xylem vess...
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Answered by Hannah W. • Biology tutor
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Describe the generation of action potentials in neurons.

When the neuron is stimulated, it causes rapid depolarisation of the cell surface membrane. This will not generate an action potential unless it is large enough to exceed the threshold potential . If it does...
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Answered by Howard R. • Biology tutor
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Why is water being a solvent important?

dilute harmful substancestransport in bloodstream and plantsfor metabolic reactions to occurseparation of substancesabsorption of ions etc.
SA
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What is the definition of a pathogen and give two examples. (3 marks)

An organism that can cause disease - e.g. virus, bacterium, fungus
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Answered by Thomas R. • Biology tutor
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Describe how an action potential is generated?

An action potential is an all or none response which has a threshold voltage which needs to be reached by the stimulus. A stimulus will call depolarisation of a nerve axon. This is caused on the entry of sod...
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Answered by Susmita N. • Biology tutor
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